United States Department of Transportation
i
Development of a congestion management system using GPS technology : volume I.
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1997-04-01
[PDF-4.99 MB]
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Alternative Title:Development of a congestion management system using GPS technology.
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Abstract:This report describes the results of a study undertaken to demonstrate the feasibility of using global positioning system( GPS) and geographic information system (CIS) technologies to measure travel time and speed data on urban highways. Compared to more traditional approaches for conducting travel time studies, which require a significant amount of manual field work and are prone to recording errors, the methodology described here dramatically increased productivity, as well as virtually eliminated data collection and data reduction errors.
The methodology described in this report includes data collection, data reduction, and data reporting procedures. The data collection procedure is based on the use of GPS receivers to automatically collect time, local coordinates, and speed every one second. This way, an accurate depiction of vehicle location and speed is obtained. The data reduction procedure is based on the aggregation ol GPS data using highway segments which are normally 0.2 miles (mi) in length. However, the model is sufficiently general so that other segment sizes can be easily accommodated. The data reporting procedure uses a GIS-based management information system to define queries, tabular reports, and color coded maps to document travel time data along the corridor segments. Examples of such data includes travel times, average speeds, minimum speeds; and delays. Color coded maps show the spatial variation of items such as speed and travel time, and are particularly suitable for explaining travel time delays and congestion issues at public meetings. Tabular reports offer a very compact way of archiving travel time and speed data along highway segments. This makes them suitable for archival and analytical purposes. The procedure to produce these tabular reports has been automated, therefore increasing the usefulness of such an approach. Reporting procedures using world wide web (WWW) resources are also implemented. These procedures allow any user with access to the Internet to select highway segments and retrieve all records associated with these segments, and to retrieve real-time data between checkpoints located on a highway corridor.
The methodology described here was used to obtain travel time and speed data needed for developing congestion management systems (CMSs) in Baton Rouge, Shreveport, and New Orleans. In Baton Rouge, 25,000 mi of travel runs were made in 155,300 segment records. In Shreveport, 844 mi of travel runs were made on a 93 mi highway network. From a total of 100 GPS data files and 85,000 GPS points recorded, use of the methodology resulted in 5,048 segment records. In New Orleans,3,805 mi of travel runs were made on a 86 mi highway network. From a total of 68 GPS data files and 322,000 GPS points recorded, use of the methodology resulted in 22,613 segment records.
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